Air sealing rewind construction for roll-type filter



R. BENNETT 3,348,366

AIR SEALING REWIND CONSTRUCTION FOR ROLL-TYPE FILTER Oct. 24, 1967 Filed Sept. 30, 1963 INVENTOR. ROBERT L. BENNETT ATTORNEY United States Patent 3,348,366 Am SEALING REWIND CONSTRUCTION FOR ROLL-TYPE FILTER Robert L. Bennett, Louisville, Ky., assignor to American Air Filter Company, Inc., Louisville, Ky., a corporation of Delaware Filed Sept. 30, 1963, Ser. No. 312,596 3 Claims. (Cl. 55-354) This invention relates to an improved base section construction for an automatic lint condenser of the general character described in US. Patent 2,881,859.

The lint condenser or filter described in the noted patent has the general form of what is commonly called a roll-type filter in which a supply roll of filter material is provided at the upper end of the air filter, is advanced in curtain form across an air stream opening, and is rewound on a rewind roll at the bottom of the filter apparatus. The filter material used in the apparatus to which this invention relates is an extremely thin, limp, flimsy material which is supported in the air stream against displacement, and is advanced across the air stream to the rewind roll, by means of a porous, endless-belt, conveyor. The rewind roll is arranged with its periphery bearing against the endless belt conveyor so that it is rotated to eflect rewinding of used material by movement of the conveyor.

While filters constructed in accordance with the noted patent have been well accepted by those who use such devices, problems have arisen in connection with sealing the lower part of the apparatus against leakage of air and lint therethrough. Consequently from time-to-time the commercial version of the device has undergone changes in the nature of adding and rearranging the sealing means in the lower part of the filter device. In fact, in some commercial versions of the filter there are at least six separate elements in the base section performing a particular sealing function.

Consequently the object of the invention is to provide a base section construction which has an improved sealing and rewind arrangement affording manufacturing savings without detracting from the performance of the filter.

In accordance with the invention, the base section is constructed to support the rewind roll for movement along a path, as the roll enlarges, which maintains the roll periphery in engagement along two horizontal lines; one of said lines being a stationary sealing line formed by the upper edge of a sealing panel, and the other line shifting upwardly along the conveyor face as the roll enlarges. The parts which contribute to the sealing and rewind functions are arranged in a particular relationship so that the transverse sealing is effected along the upper edge of the panel and the rewind drive operation is attained with a simplified construction.

The invention will be described in some detail in connection with the accompanying drawing illustrating an embodiment thereof by way of example, and wherein:

FIGURE 1 is a broken, side elevational view of an automatic air filter of the character incorporating the invention, with certain major interior parts being shown in broken lines;

FIGURE 2 is a sectional View of the base section taken in a vertical plane parallel to the direction of air flow through the filter;

FIGURE 3 is a fragmentary front isometric view illustrating the relationship of the parts of the base section; and,

FIGURE 4 is fragmentary front sectional view corresponding to one taken along the line 44 of FIG. 2.

The embodiment of the filter illustrated in the drawing generally comprises a top supply roll section 10, a

ice

base section 12, and an open-faced intermediate section 14 which generally frames the vertical edges of the air flow zone. An upright, endless belt or conveyor 16 is mounted to be moved about an upper roller 18 in the top section, and a lower roller 20 in the base section. The belt is of openwork construction and serves to move the filter material through the intermediate section air flow zone as well as to support it against displacement by air flowing in the direction indicated in FIGURE 1.

The preferred filter material is of a thin, limp, flimsy character as described in US. Patent 2,881,859 and is supplied in the form of a roll 22 which is rotatably mounted in the top section. The filter material 24 is threaded off the roll, advanced into the intermediate section and directed downwardly along the upstream flight of the endless conveyor 16, and is then attached for rewinding to a rotatable rewind core 26 located in the base section 12 of the filter apparatus.

Referring now to FIGURES 2-4 illustrating details of the base section 12, its framing members include a bottom wall 28, opposite side walls 30 having inwardly directed flanges 32 along their upper edges, a rear lower cross member 34 having the cross-sectional shape of a channel, and an upper cross member 36 which is Z-shaped in cross section.

The side members 38 which frame the intermediate section 14 vertical edges are generally channel-shaped in cross section, as best shown in FIGURE 3, and are mounted on top of the base section with the bottom ends of the side members secured by bolts 40 to the top flanges 32 of the base section side walls.

A series of vertically-extending, horizontally-spaced, wires 42 have their bottom ends secured to the cross member 36 in the base section, and have their top ends secured to a similar cross member (not shown) in the top section to provide a back-up grid for the upstream flight of the conveyor 16. The vertical edges of the upstream flight of the conveyor '16 are supported and track in inwardly-open channels 4-4 attached to the respectively opposite inner faces of the side members 38. The vertical edges of the filter material 24 also track in these side channels which also serve to seal against passage of air therearound. Extensions 46 of the side channels are provided in the base section and are directed downwardly along the inner faces of the base section sidewalls 30. The rear flange of the extension 46 terminates slightly above the bottom roller 20 while the forward flange extends down some distance further and has a tab portion 48 (FIG. 4) bent out forwardly and downwardly so that the edges of the filter material may leave the channel extensions 46 to be rewound around the core 26. As is also shown in FIG. 4, the ends of the rewind core 26 are spaced inwardly from the edge of the channel extensions 46 so that the core is not held away from the conveyor 16 and roller 28. Thus the marginal edges of the filter material 24 assume a ruflled form at the ends of the roll.

Each of the side walls 30 carries a bearing 50 on its inner face in which the opposite ends of the bottom roller 20 are journalled. The roller 20' is provided with alternating toothed and smooth segments (illustrated in FIG. 3) arranged so that the toothed segments mesh with certain columns of the endless belt to drive it. The drive for the bottom roller is provided by external means not shown.

To prevent air flow from passing below the roller 20, an upright wall 52 is provided to extend upwardly from the bottom wall 218 with its upper horizontal margin flanged re-arwardly as shown. The upper forward edge 54 of this panel serves as a seal against which the periphery of the rewind roll (also designated as 26) bears.

The core 26 of the rewind roll is a hollow metal shaft having a diameter somewhat larger than the diameter of the bottom roller 20. The ends of the core are closed by end caps welded thereto, and small diameter spindles 5 6 are welded to extend outwardly from the end caps in alignment with the axis of the core. These spindles ride in tracks formed by inwardly-open channels 58 secured to the inner faces of each of the side walls 30. For reasons to be later explained, the web of the channel 58 is substantially wider than the diameter of the spindles. A wire spring 60 with a spiral bottom end attached to the side wall 30 is provided adjacent each of the side walls in a position in which the arm of the spring bears in a rearward direction to force the spindles 56 and rewind core or roll 26 toward the roller and the sealing edge 54. The spring 60 may be pulled back and lodged against the forward ends of the channel 58, as shown by the broken line spring position in FIG. 2, when the rewind roll is to be removed from the base section.

The concept of sealing the base section against leakage of unfiltered air and contaminants therethrough entails locating the rewind roll 26 for a path of movement such that as its periphery enlarges (as indicated by the long and short dash line outline of the roll in FIG. 2) the periphery always bears against the sealing edge 54. However, since the rewind roll is also driven by having its periphery bear against the conveyor adjacent the bottom roller 20, it is also necessary that the engagement of the rewind roll against the conveyor be maintained. It will also be appreciated that as the rewind roll enlarges due to additional filter material being wound thereon, clearance must be provided for such enlargement.

As shown, the channels '58 in which the spindles 2-6 of the rewind core ride are inclined so that as the circumference of the rewind roll enlarges and its axis moves forwardly, the roll will also move upwardly to provide clearance between the bottom of the roll and the bottom wall of the base section. The inclination of the channels 5-8 also results in gravity urging the rewind roll in a rearward direction against the conveyor and sealing edge 54, this gravitational force of course being normally supplemented by the force of the wire spring 60.

The preferred disposition of the channels 58 is perhaps best explained with reference to a plane (hereinafter called the sealing-driving plane) which passes through the upper edge 54 of the sealing Wall 52 and is tangent to the forward circumferential port-ion of the bottom roller 20. The two channels are located with their axes on the same level and disposed substantially normal to this sealing-driving plane, and with the plane in which the channel axes lie bisecting that vertical dimension of the sealing-driving plane bounded along the top by the line of tangency with the roller 29 and along the bottom by the sealing edge '54. While the term substantially normal has been used in a definitive sense, it is noted that currently preferred practice is to tilt the channels upwardly in the order of from 3l0 above the plane normal to the sealing plane to insure the driving engagement between the rewind roll periphery and the conveyor at all times.

With the bare core 26 having a diameter approximately half again as great as the diameter of the bottom roller, it has been determined that the path of movement of the axis of the rewind roll during enlargement to the point where the used filter material is stripped oh. the rewind roll is a nearly straight line. To the extent that the path is not straight, the sealing and driving engagement are accommodated by making the web of the channels 58 somewhat wider than the diameter of the spindles 56 of the rewind roll. Thus with the springs 60 urging the rewind roll rearwardly, the roll seeks a position of stability in which its periphery bears against two spaced lines-one being the driving engagement line, and the other being the sealing engagement line. This accommodating arrangement not only compensates for the path of movement not being a straight line, but also accommodates variations in the rewind roll periphery curvature resulting from differences in thickness of the layer of contaminants along the lengths of the filter material. Also, depending upon the character of the contaminant collected, the periphery of the enlarged rewind roll will normally flatten out to some degree where it is pressed against the surface of the conveyor adjacent the forward portion of the bottom roller, and also where it is pressed against the sealing edge 54.

In determining the exact location of the channels, the following method may be used. The upper edge 54 of the sealing panel is in the form of an arc of small radius. The point where the axis of the core 26 will be when no filter material is wound on the core is found by striking one are (having a radius equal to the sum of radii of the core 26 and the upper edge 54 are) from the center point of the upper edge 54 arc, and striking another are (having a radius equal to the sum of radii of the core 26 and roller 20) from the center point of the roller 20. Additional pairs of arcs are then struck using successively larger radii for the core or rewind roll radius. The suc cessive points where each pair of arcs intersect traces the theoretical path of movement of the rewind roll. The disposition of the channels closely follows this theoretical path, with any departure being governed primarily by the extent to which the roll 26 presses against the conveyor 16 above the level of the axis of the roller 20.

The invention claimed is:

1. In a roll-type air filter including a filter media supply section, a filter media rewind section, an air passage intermediate the supply section and said rewind section through which a stream of air to be filtered is passed, filter media extending through said air passage from said supply section to said rewind section so said stream of air is passed through said media in said air passage in filtering relation, media conveyor means including an endless belt conveyor supporting said media in said air passage and moving said filter media from said supply section through said air passage to said filter media rewind section, said conveyor passing around and in contact with roller means disposed in said rewind section, and means sealing the sides of said media passed through said air passage and preventing air leakage around the sides of said media,

(a) a filter media rewind roll receiving and rewinding filter media which has passed through said air passage section from said supply section, said rewind roll having opposite end spindles and being disposed generally parallel to said roller and upstream of said roller, relative to the direction of flow of gas to be filtered through said air passage, and means urging a peripheral section of said rewind roll, including filter 'media wound thereon, against said conveyor and urging said conveyor against said roller means at the nip formed at the v line of contact between said conveyor and said rewind roll periphery, said line of contact defining a rewind roll driving engagement line which is tangential to said rewind roll at the point of contact of said rewind roll and said conveyor;

(b) a stationary panel extending continuously across the width of said rewind section and rigidly fixed to said rewind section in sealing relation, to prevent air to be filtered from passing around said stationary panel, said panel terminating adjacent said nip in an upper sealing edge parallel to the axis of said rewind roll and said sealing edge continuously contacting media wound on said rewind roll preventing the passage of air between said sealing edge and said rewind roll; and,

(c) spindle receiving channel means forming substantially straight channels, one of said channel means being disposed on each of the opposite sides of said rewind section receiving and supporting said spindles of said rewind roll and said channel means being disposed within said rewind section, said spindles of said rewind roll removing through said channel means in response to accumulation of filter media on said rewind roll while maintaining contact between said rewind roll, including said media wound thereon, and both said sealing edge of said stationary panel and said conveyor means along said 5 driving engagement line.

2. The construction according to claim 1 wherein: said channels are inwardly directed and the width of each of said channels is greater than the diameter of said spindles of each rewind roll.

3. The construction according to claim 1 wherein said rewind section includes cooperative spring means adapted to urge said rewind roll, including filter media wound thereon, against said conveyor means to urge said belt conveyor against said roller means.

References Cited UNITED STATES PATENTS 1,503,858 8/1924 Steiner 242-62 X 1,783,181 12/1930 Brikholz 55354 X 2,016,991 10/1935 Dollinger 354 2,119,978 6/1938 Wolthuis et a1. 55354 2,237,654 4/ 1941 Cohn et a1. 242 2,271,401 1/ 1942 Sainty 55290 X 6 11/ 1950 Thomson 242-65 10/1951 Campbell 242-65 9/1957 Rivers 55-354 X 10/ 1957 Hofstetter 55354 6/ 1958 Clem 24265 4/ 1959 Nutting 55354 X 4/1959 Dyer 55354 5 1961 Rockstrom 24265 10/1961 Palmore 55354 2/ 1963 Wells et al 24276 X 7/1966 Krause 55501 X FOREIGN PATENTS 5 1937 Austria. 7/ 1961 Austria. -8 1961 Austria. 2/ 1958 Canada. 3/ 1956 Great Britain. 11/1956 Great Britain. :8/ 1962 Great Britain.

HARRY B. THORNTON, Primary Examiner. D. TALBERT, Assistant Examiner. 

1. IN A ROLL-TYPE AIR FILTER INCLUDING A FILTER MEDIA SUPPLY SECTION, A FILTER MEDIA REWIND SECTION, AN AIR PASSAGE INTERMEDIATE THE SUPPLY SECTION AND SAID REWIND SECTION THROUGH WHICH A STREAM OF AIR TO BE FILTERED IS PASSED, FILTER MEDIA EXTENDING THROUGH SAID AIR PASSAGE FROM SAID SUPPLY SECTION TO SAID REWIND SECTION SO SAID STREAM OF AIR IS PASSED THROUGH SAID MEDIA IN SAID AIR PASSAGE IN FILTERING RELATION, MEDIA CONVEYOR MEANS INCLUDING AN ENDLESS BELT CONVEYOR SUPPORTING SAID MEDIA IN SAID AIR PASSAGE AND MOVING SAID FILTER MEDIA FROM SAID SUPPLY SECTION THROUGH SAID AIR PASSAGE TO SAID FILTER MEDIA REWIND SECTION, SAID CONVEYOR PASSING AROUND AND IN CONTACT WITH ROLLER MEANS DISPOSED IN SAID REWIND SECTION, AND MEANS SEALING THE SIDES OF SAID MEDIA PASSED THROUGH SAID AIR PASSAGE AND PREVENTING AIR LEAKAGE AROUND THE SIDES OF SAID MEDIA, (A) A FILTER MEDIA REWIND ROLL RECEIVING AND REWINDING FILTER MEDIA WHICH HAS PASSED THROUGH SAID AIR PASSAGE SECTION FROM SAID SUPPLY SECTION, SAID REWIND ROLL HAVING OPOSITE END SPINDLES AND BEING DISPOSED GENERALLY PARALLEL TO SAID ROLLER AND UPSTREAM OF SAID ROLLER, RELATIVE TO THE DIRECTION OF FLOW OF GAS TO BE FILTERED THROUGH SAID AIR PASSAGE, AND MEANS URGING A PERIPHERAL SECTION OF SAID REWIND ROLL, INCLUDING FILTER MEDIA WOUND THEREON, AGAINST SAID CONVEYOR AND URGING SAID CONVEYOR AGAINST SAID ROLLER MEANS AT THE NIP FORMED AT THE LINE OF CONTACT BETWEEN SAID CONVEYOR AND SAID REWIND ROLL PERIPHERY, SAID LINE OF CONTACT DEFINING A REWIND ROLL DRIVING ENGAGEMENT LINE WHICH IS TANGENTIAL TO SAID REWIND ROLL AT THE POINT OF CONTACT OF SAID REWIND ROLL AND SAID CONVEYOR; (B) A STATIONARY PANEL EXTENDING CONTINUOUSLY ACROSS THE WIDTH OF SAID REWIND SECTION RELATION, TO PREVENT AIR TO BE FILTERED FROM PASSING AROUND SAID STATIONARY PANEL, SAID PANEL TERMINATING ADJACENT SAID NIP IN AN UPPER SEALING EDGE PARALLEL TO THE AXIS OF SAID REWIND ROLL AND SAID SEALING EDGE CONTINUOUSLY CONTACTING MEDIA WOUND ON SAID REWIND ROLL PREVENTING THE PASSAGE OF AIR BETWEEN SAID SEALING EDGE AND SAID REWIND ROLL; AND, (C) SPINDLE RECEIVING CHANNEL MEANS FORMING SUBSTANTIALLY STRAIGHT CHANNELS, ONE OF SAID CHANNEL MEANS BEING DISPOSED ON EACH OF THE OPPOSITE SIDES OF SAID REWIND SECTION RECEIVING AND SUPPORTING SAID SPINDLES OF SAID REWIND ROLL AND SAID CHANNEL MEANS BEING DISPOSED WITHIN SAID REWIND SECTION, SAID SPINDLES OF SAID REWIND ROLL REMOVING THROUGH SAID CHANNEL MEANS IN RESPONSE TO ACCUMULATION OF FILTER MEDIA ON SAID REWIND ROLL WHILE MAINTAINING CONTACT BETWEEN SAID REWIND ROLL, INCLUDING SAID MEDIA WOUND THEREON, AND BOTH SAID SEALING EDGE OF SAID STATIONARY PANEL AND SAID CONVEYOR MEANS ALONG SAID DRIVING ENGAGEMENT LINE. 